Flexible storage block for a solid state drive (ssd)-based file system

ABSTRACT

Techniques generally described are related to a flexible storage block based on solid state devices. One example method to update data stored in a storage block may include maintaining, by a flash storage module, a cluster link in the storage block for storing a file, wherein the cluster link links together a plurality of data clusters that are storage spaces provided by one or more solid state devices. The method may include, in response to a first request to update data stored in a first data cluster amongst the plurality of data clusters, allocating a second data cluster to store the updated data. The method may further include linking the second data cluster to the cluster link, wherein the linking the second data cluster to the cluster link invalidates the first data cluster in the cluster link.

BACKGROUND

The performance of a file system may be highly dependent on the latencyor throughput of a data storage device on which the file system isbased. Solid state devices may offer good read performance, good randomaccess speed, and low energy consumption in providing storage services.However, data throughput of the solid state device may be limited by thethroughput of the interface (e.g., USB 2.0 or SATA) that the solid statedevice is coupled with. The performance of the solid state device mayalso be unbalanced depending on whether the solid state device isperforming a read operation or an update operation.

According to one example statistical analysis, the percentage of smallfiles (files with sizes that are under 16 KB) in a particular filesystem may be higher than 50%. In some situations, up to 88% of filesmay be small files in certain types of file systems. Since these filesystems may allocate at a minimum one flash page for storing a fileregardless of the size of the file, the probability of wasting storagespace in the solid state device may be great, as most of the storedfiles have sizes that are smaller than the size of the flash page.

SUMMARY

In accordance with some embodiments of the present disclosure, a methodto update data stored in a storage block may include maintaining, by aflash storage module, a cluster link in the storage block to store afile, wherein the cluster link links together a plurality of dataclusters that are storage spaces provided by one or more solid statedevices. The method may include, in response to a first request toupdate data stored in a first data cluster amongst the plurality of dataclusters, allocating, by the flash storage module, a second data clusterto store the updated data. The method may further include linking, bythe flash storage module, the second data cluster to the cluster link,wherein the linking the second data cluster to the cluster linkinvalidates the first data cluster in the cluster link.

In accordance with other embodiments of the present disclosure, anothermethod to store data in a storage volume may include maintaining, by aflash storage module, a plurality of storage blocks utilizing storagespaces provided by one or more solid state devices. The method mayinclude constructing, by the flash storage module, a cluster link tostore a file, wherein the cluster link links together a plurality ofdata clusters each of which is a storage location that is located in oneof the plurality of storage blocks. In response to an update request toupdate the file, the method may include identifying, by the flashstorage module, a first data cluster in the plurality of data clustersthat is associated with updated data in the file. The method may furtherinclude allocating, by the flash storage module, a second data clusterin any one of the plurality of storage blocks that has available spaceto store the updated data, and linking, by the flash storage module, thesecond data cluster to the cluster link, wherein the linking the seconddata cluster to the cluster link invalidates the first data cluster inthe cluster link.

In accordance with further embodiments of the present disclosure, asystem to manage flash data storage may include a solid state deviceconfigured to provide a plurality of flash pages. The system may furtherinclude a flash storage module coupled with the solid state device. Theflash storage module may be configured to maintain a storage blockutilizing storage spaces provided by the solid state device, andconstruct a cluster link to store a file in the storage block, whereinthe cluster link links together a plurality of data clusters each ofwhich utilizes one of the plurality of flash pages to store dataassociated with the file. In response to a request to update data storedin a first data cluster amongst the plurality of data clusters, theflash storage module may further be configured to allocate a second datacluster in the storage block to store the updated data, and link thesecond data cluster to the cluster link to invalidate the first datacluster.

In accordance with additional embodiments of the present disclosure, anon-transitory computer-readable storage medium may have a set ofinstructions which, when executed by a computing processor, cause thecomputing processor to perform a method to update data stored in astorage block. The method may include maintaining, by a flash storagemodule, a cluster link in the storage block to store a file, wherein thecluster link links together a plurality of data clusters that arestorage spaces provided by one or more solid state devices. The methodmay include, in response to a first request to update data stored in afirst data cluster amongst the plurality of data clusters, allocating,by the flash storage module, a second data cluster to the cluster linkto store the updated data. The method may further include linking, bythe flash storage module, the second data cluster to the cluster link,wherein the linking the second data cluster to the cluster linkinvalidates the first data cluster in the cluster link.

In accordance with additional embodiments of the present disclosure, anon-transitory computer-readable storage medium may have a set ofinstructions which, when executed by a computing processor, cause thecomputing processor to perform a method to store data in a storagevolume. The method may include maintaining, by a flash storage module, aplurality of storage blocks utilizing storage spaces provided by one ormore solid state devices, and constructing, by the flash storage module,a cluster link to store a file, wherein the cluster link links togethera plurality of data clusters each of which is a storage location that islocated in one of the plurality of storage blocks. In response to anupdate request to update the file, the method may include identifying,by the flash storage module, a first data cluster in the plurality ofdata clusters that is associated with updated data in the file;allocating, by the flash storage module, a second data cluster in anyone of the plurality of storage blocks that has available space to storethe updated data; and linking, by the flash storage module, the seconddata cluster to the cluster link, wherein the linking the second datacluster to the cluster link invalidates the first data cluster in thecluster link.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram illustrating embodiments of a storagemanagement system configured to provide flash-based flexible storageblocks;

FIG. 2A shows illustrative embodiments of a flexible storage blockconfigured with a double-linking mechanism;

FIG. 2B shows illustrative scenarios of update operations performed on acluster link;

FIG. 3 shows illustrative embodiments of a flexible storage volumehaving multiple flexible storage blocks;

FIG. 4 shows a flow diagram of an illustrative embodiment of a processto update data stored in a flexible storage block;

FIG. 5 shows a flow diagram of an illustrative embodiment of a processto maintain a flexible storage volume having multiple flexible storageblocks;

FIG. 6 shows an illustrative embodiment of an example computer programproduct; and

FIG. 7 shows a block diagram of an illustrative embodiment of an examplecomputer system, all arranged in accordance to at least some embodimentsof the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here. The aspects of the present disclosure, as generallydescribed herein, and illustrated in the Figures, can be arranged,substituted, combined, and designed in a wide variety of differentconfigurations, all of which are explicitly contemplated herein.

This disclosure is drawn, inter alia, to methods, apparatuses, computerprograms, and systems related to a flexible storage block based on solidstate devices.

FIG. 1 shows a block diagram illustrating embodiments of a storagemanagement system configured to provide flash-based flexible storageblocks. In FIG. 1, a flexible storage management system 110 may be acomputer system configured to store and retrieve data on behalf of oneor more client applications (not shown in FIG. 1). The flexible storagemanagement system 110 may be configured with one or more solid statedevices 120 (such as SSD-based devices/configurations), and a flashstorage module 122 operatively coupled to the solid state devices 120and configured to process file-level data requests and/or block-leveldata requests received from the client application(s). The flexiblestorage management system 110 may be implemented using a storage server,personal computer (PC), workstation, laptop, tablet PC, handheldcomputing/communication device, cell phone, smart phone, or otherelectronic device. Moreover, the flexible storage management system 110may be implemented based on a computing device further described below.

In some embodiments, the flash storage module 122 may configure thenon-volatile flash memories in the solid state devices 110 into a set offlash pages 121, each of which may have a size of e.g., 2 K, 4 K, or 8 Kbytes or other size. The flash storage module 122 may then performflash-page based read and write operations on the solid state devices120, in which each read or write operation may affect at least one flashpage 121. The flash storage module 122 may further configure multipleflash pages 121 (e.g., 32 to 128 flash pages) into a flash block, andperform flash-block based update and erase operations on the solid statedevices 120. A flash-block based operation may affect at least one flashblock at a time.

In some embodiments, according to the characteristics of the flashmemory, a blank flash page 121 with no data stored may initially contain“1” bits and no “0” bits. A “write operation” (an operation to storedata to a blank flash page) performed on a blank flash page may changeone or more of the “1” bits in the blank flash page to “0” bits. Afterthe write operation, the flash storage module 122 may perform multipleread operations to retrieve data from the flash page. Optionally, theflash storage module 122 may perform a “partial-update operation” on aflash page that has gone through a write operation. The partial-updateoperation may change one or more of the remaining “1” bits in the flashpage into “0” bits, but may not change any “0” bit into “1” bit. Forexample, a flash page may initially contain “111” in its flash storageunits. A write operation may store “110” to the flash page, and asubsequent partial-update operation may change the flash page to “100”,“010”, or “000.” However, no write or partial-update operation maychange any “0” bits in the flash page back to “1” bits.

In some embodiments, to change one or more “0” bits in a specific flashpage to “1” bits, the flexible storage module may perform an updateoperation on the flash block where the specific flash page is located.The “update operation” may be a combination of an “erase” operationperformed on the flash block followed by write operations on the flashblock including a write operation on the specific flash page.Specifically, the erase operation may “flash” all the “0” bits in theflash block into “1” bits, thereby erasing all data stored in the flashblock. Afterward, the flash storage module may restore the dataoriginally stored in the flash pages (except the specific flash page) ofthe flash block, and then apply the write operation to store the changeddata to the specific flash page. Thus, updating a single flash page mayinvolve the erasing and rewriting of a whole flash-block of data thespecific flash page contained therein. As a result, a conventionalupdate/erase operation may have a low throughput as compared to aread/write operation.

In some embodiments, the flash storage module 122 may configure theflash pages 121 into one or more flexible storage volumes 160, each ofwhich may contain one or more flexible storage blocks 130, 140, and 150,etc. Three flexible storage blocks 130, 140, and 150 are shown in FIG. 1for purposes of illustration, and any suitable number for flexiblestorage blocks may be provided. Further, the flash storage module 122may configure one or more data clusters (e.g., data clusters 131, 132,and 133), which are data in one of the flexible storage blocks 130, 140,and 150, using flash memories provided by one or more flash pages 121(e.g., 32 to thousands of flash pages). The size of the data clusters inone flexible storage block (e.g., the flexible storage block 130) maydiffer from the size of the data clusters in another flexible storage(e.g., the flexible storage block 140). The flexible storage blocks inthe flexible storage volume 160 may form one or more link-lists(referred to as block links), with one flexible storage block referringto the next flexible storage block on each of the block link. Further,the data clusters in a single flexible storage block may also form oneor more link-lists (referred to as cluster links).

In some embodiments, compared to a conventional write operation whichuses a minimum of one flash page 121, the flexible storage module 122may utilize one or more data clusters in a flexible storage block tostore a piece of data. By configuring the size of the data cluster to besmaller than the size of the flash page 121, the flexible storage module122 may store multiple small files to a space that is conventionallyallocated to store a single small file. Further, the flash storagemodule 122 may update the data stored in a data cluster by “marking” thedata cluster as “invalid”, and allocate a new data cluster to store theupdated data. As a result, the flash storage module 122 no longer needsto erase a whole flash block of data in order to update a single pieceof data. Thus, the flexible storage blocks and data clusters not onlyprovide better utilization of the flash storage spaces for the solidstate devices 120 than the conventional flash pages and flash blocks do,but also greatly improve the performance of update operations for thesolid state devices 120.

FIG. 2A shows illustrative embodiments of a flexible storage blockconfigured with a double-linking mechanism. In FIG. 2A, a flexiblestorage block 210, which may be similar to the flexible storage block130, 140, or 150 of FIG. 1, may contain, among other fields andcomponents, an “index” field 211, a “next pointer” field 212, a“configuration” field 213, a “file allocation table” (“FAT”) 214, an“availability map” 215, and a “validity map” 216. Further, the flexiblestorage block 210 may contain one or more data clusters 220, 230, and240, each of which may be similar to the data cluster 131, 132, or 133of FIG. 1. Each of the data clusters 220, 230, and 240 may contain,among other fields, a “first pointer” field (e.g., first pointer 221), a“second pointer” field (e.g., second pointer 222), a “FAT index” field(e.g., FAT index 223), and a “data” section (e.g., data section 224).

In some embodiments, a flash storage module (similar to the flashstorage module 122 of FIG. 1, not shown in FIG. 2A) may be configured toallocate the flexible storage block 210 based on a particular andconfigurable set of flash pages (e.g., 32 flash pages). The flashstorage module may assign a unique identifier to an “index” field 211 ofthe flexible storage block 210, in order to identify the flexiblestorage block 210 in a flexible storage volume (such as the flexiblestorage volume 160 of FIG. 1, not shown in FIG. 2A). The flash storagemodule may allocate an additional flexible storage block in the flexiblestorage volume, and utilize the “next pointer” field 212 to referencethe additional flexible storage block from the flexible storage block210. The details of the next pointer field 212 and the flexible storagevolume may be further described below.

In some embodiments, the flash storage module may construct multipledata clusters in the flexible storage block 210. Each data cluster maybe deemed a storage unit configured to store a piece of data. Further,each data cluster may be configured with linking mechanisms to link withother data clusters. The size of the data cluster may be particular andconfigurable based on the “configuration” field 213 in the flexiblestorage block 210. In other words, the flash storage module mayconstruct a data cluster with a size that is defined by theconfiguration field 213. For example, the flash storage module mayconstruct a data cluster having the same size as a flash page.Alternatively or additionally, the flash storage module may create adata cluster with a size that is smaller than the size of the flashpage. Having a smaller sized data cluster allows more small files to bestored in the flexible storage block 210, since each small file may takeat a minimum one data cluster for storage. In some embodiments, the sizeof the data cluster in one flexible storage block 210 may be differentfrom the size of the data cluster in another flexible storage block, aseach flexible storage block has its own configuration field 213 toconfigure the size of the data clusters contained therein.

In some embodiments, the flash storage module may utilize the fileallocation table (‘FAT”) 214 to store/retrieve data to/from the one ormore data clusters 220, 230, and 240. For example, a file system 280(which may be a file system in Microsoft Windows®, Linux®, Solaris® x86,NetWare, FreeBSD, Apple® iOS, Android®, or any other operating system)may contain one or more files 281 and 282. Each of the files 281 and 282may be deemed a logical set of data having a size ranging from one ormore bytes to any size that is supported by the file system 280. Theflash storage module may be configured to provide data storage servicesfor the file system 280. In other words, the flash storage module maystore the logical set of data contained in a specific file (e.g., file281) to a cluster link of data clusters 220, 230, and 240 in a flexiblestorage block 210 or in multiple flexible storage blocks. Thus, eachcluster link may be deemed a flexible storage structure to store thespecific file. Afterward, the flash storage module may utilize the FAT214 to retrieve the logical set of data from the cluster link of dataclusters when the file system 280 requests for the file 281.

In some embodiments, the FAT 214 may contain a set of “FAT entries”,each of which associates a specific file in the file system 280 with acorresponding data cluster in the flexible storage block 210. Forexample, the file 281 may be associated with the FAT entry 217, and theflash storage module may be configured to identify the FAT entry 217from the FAT 214 based on a logical address of the file 281. Based onthe FAT entry 217, the flash storage module may locate the data cluster220 from the flexible storage block 210. Specifically, the FAT entry 217may be assigned with a “cluster address” associated with an address ofthe data cluster 220 in the flexible storage block 210. Thus, the flashstorage module may retrieve the cluster address from the FAT entry 217,and utilize this cluster address to locate the specific data cluster220. Afterward, the flash storage module may access data which belongsto the file 281, and is stored in the data section 224 of the datacluster 220.

In some embodiments, a single data cluster 220 may not be sufficient tostore all the data for the file 281. In this case, the flash storagemodule may construct a cluster link having multiple data clusters tostore the data for the file 281. The “cluster link” may be an array or alink-list of data clusters distributed in one or more flexible storageblocks. Each data cluster in the cluster link may have a pointerconfigured to reference a subsequent data cluster in the cluster link,which may be located in any place in the flexible storage block 210 orin another flexible storage block in the flexible storage volume. In oneembodiment, the cluster link may have a data cluster acting as a “head”of the cluster link, and another data cluster acting as a “tail” of thecluster link. In other words, no other data cluster references the headdata cluster, and the tail data cluster does not reference another datacluster. Any of the other data clusters in the cluster link that isneither “head” nor “tail” may have a “previous” data cluster in thecluster link referencing it, and may reference a “next” data cluster inthe cluster link. Thus, the data cluster 220 that is referenced by theFAT entry 217 in the FAT 214 may be a “head” data cluster for a specificcluster link in the flexible storage block 210. In other embodiments,any one or more of the data clusters may have a pointer that points toat least one other data cluster in the cluster link, where the at leastone other data cluster is not necessarily the immediately “previous” orthe immediately “next” data cluster, such that the pointer(s) in the oneor more data clusters need not refer to data clusters that arein-sequence.

In some embodiments, the flash storage module may allocate a second datacluster 230 (or more data clusters) in the flexible storage block 210 tostore additional data in the file 281 that cannot be stored in a singledata cluster 220. After allocation of the second data cluster 230, theflash storage module may store the cluster address of the data cluster230 in the first pointer field 221 of the data cluster 220, and storethe additional data of the file 281 to the data section 234 of the datacluster 230. Thus, the first pointer field 221 may serve as a pointer toreference the second data cluster 230 from the data cluster 220. And theflash storage module may locate data for the file 281 by using the FATentry 217 to first identify the data cluster 220, and using the firstpointer field 221 of the data cluster 220 to identify the data cluster230.

In some embodiments, the flash storage module may store the clusteraddress of the data cluster 230 to a FAT entry 218 in the FAT 214, andstore the reference to the FAT entry 218 to the first pointer field 221of the data cluster 220. Thus, the flash storage module may be able tolocate the data cluster 230 by identifying the FAT entry 218 based onthe first pointer field 221 of the data cluster 220, and identifying thedata cluster 230 using the cluster address stored in the FAT 218. Inother words, the flash storage module may utilize the FAT entries in theFAT 214 as a part of the linking mechanism for the cluster link in theflexible storage block 210.

In some embodiments, the data cluster 220 may contain a FAT index 223configured to reconstruct the FAT 214 when the FAT 214 becomesinaccessible or corrupted. Specifically, the FAT index 223 may containsome or all the information stored in the FAT entry 217, and the flashstorage module may retrieve the information from the FAT index 223, andreconstruct the FAT entry 217 in the FAT 214. Alternatively, the FATindex 223 may further contain relevant information associated with theflexible storage block 210, so that the flash storage module mayreconstruct the flexible storage block 210 if any of its meta-data aremissing or corrupted.

In some embodiments, the flash storage module may receive a datarequest, seeking to update “old data” stored in a specific data clusterwith “update data” transmitted via the request. The flash storage modulemay perform a partial-update operation to store the update data to theflexible storage block 210, while avoiding performing a conventionalupdate operation to a whole flash block. Specifically, thepartial-update operation may involve the marking of the “old data” asinvalid, and the redirecting of any request for the “old data” to the“update data” stored in the flexible storage block 210. Further, themarking of the old data and the redirecting to the update data may notinvolve updating any “0” bits in the flexible storage block 210 to “1”bits.

In some embodiments, the flash storage module may utilize a secondlinking mechanism to mark the old data as invalid and redirect to theupdate data. Specifically, the second linking mechanism may be the“second pointer” fields in the data clusters, each second pointer fieldhaving a default/initial value (e.g., 0xFFFF) with one or more “1” bitsand no “0” bit. For a specific data cluster, its second pointer fieldhaving the default/initial value may indicate that the specific datacluster is valid. To update the second pointer field to reference theupdate data, the flash storage module may perform a partial-updateoperation on the flash page that contains the second pointer field. Thepartial-update operation may change one or more “1” bits in the initialvalue to “0” bits. As a result, the second pointer field may contain adifferent value than the default/initial value, and the different valuemay indicate that the specific data cluster is no longer valid.

For example, the flash storage module may receive an update request toupdate data stored in the file 281. The flash storage module mayidentify the cluster link (including data clusters 220 and 230) thatcontains data for the file 281, and identify that the update data may belocated in the data cluster 230. The flash storage module may thenallocate a new data cluster 240 in the flexible storage block 210, andstore the update data to the data section 244 of the data cluster 240.Afterward, the flash storage module may assign the first pointer field241 of the data cluster 240 with values in the first pointer field 231of the data cluster 230, and update the second pointer field 232 of thedata cluster 230 to reference the data cluster 240. The updating of thesecond pointer field 232 may invalidate the data cluster 230. And thedata cluster 240 may now act as a substitute of the data cluster 230 inthe cluster link.

Subsequently, when the flash storage module receives a read request fordata associated with the file 281, it may identify the cluster link (nowincluding data clusters 220, 230, and 240) associated with the file 281,and retrieve data by traversing the cluster link. The flash storagemodule may first locate the data cluster 220 and determine that the datacluster 220 is valid. The flash storage module may then retrieve datafrom the data section 224 of the data cluster 220, and identify the datacluster 230 based on the first pointer field 221 of the data cluster220. Upon a determination that the data cluster 230 is no longer validdue to its second pointer field 232 not equaling to the default/initialvalue, the flash storage module may utilize the second pointer field 232to locate the data cluster 240. Once the flash storage module determinesthat the data cluster 240 is valid, it may retrieve data from the datasection 244 of the data cluster 240.

FIG. 2B shows illustrative scenarios of update operations performed on acluster link. In some embodiments, the flash storage module may receivean update request to append data to a file, which is stored in a clusterlink 250 including data clusters 251, 252, 253, and 254. In this case,the flash storage module may allocate one or more new data clusters(e.g., data cluster 255) for the appending data, either in the sameflexible data block (e.g., flexible data block 210 of FIG. 2A) as thedata clusters 251, 252, 253, and 254, or in a different flexible datablock. Afterward, the flash storage module may add the new data cluster255 to the cluster link 250 by assigning the first pointer field of thedata cluster 254 to point to the new data cluster 255.

In some embodiment, the flash storage module may receive an updaterequest to update data in a file, which may be stored in a cluster link260 including data clusters 261, 262, 263, and 264. In this case, theflash storage module may identify that the “update data” being locatedin the existing data clusters 262 and 263, and allocate one or more newdata clusters (e.g., data clusters 265 and 266) for the update data.Afterward, the flash storage module may add the new data clusters 265and 266 to the cluster link 260 by assigning the second pointer of thedata cluster 262 to point to the data cluster 265, assigning the firstpointer of the data cluster 265 to point to the data cluster 266. Thefirst pointer of the data cluster 266 may also be copied from the firstpointer of the data cluster 263. Thus, the data cluster 262 may bedeemed invalid since its second pointer no longer equals to the initialvalue. Further, the data cluster 263, which is referenced by the firstpointer of the data cluster 262, may no longer be accessible via thedata cluster 262, and may optionally be deemed invalid. As a result, theeffective cluster link 260 may contain data clusters 261, 265, 266, and264. It should be noted that the first pointer of the data cluster 266may not point to the data cluster 264 and may instead point to a datacluster 267. In some embodiments, if the size of the data cluster 265and the size of the data cluster 266 equal to the size of the datacluster 262 and the size of the data cluster 263, respectively, then thedata cluster 266 may be linked to the data cluster 264.

In some embodiment, the flash storage module may receive an updaterequest to delete data from a file, which is stored in a cluster link270 including data clusters 271, 272, 273, and 274. In this case, theflash storage module may identify that the “delete data” being locatedin the existing data cluster 273. Afterward, the flash storage modulemay effectively “remove” the data clusters 273 from the cluster link 270by assigning the second pointer of the data cluster 273 to point to thedata cluster 274. Thus, the data cluster 273 may be deemed invalid sinceits second pointer no longer equals to the default/initial value. Andthe effective update cluster link 270 may contain data clusters 271,272, and 274. Thus, by using a flexible storage block with double-linkmechanism, the flash storage module may update the data stored in theflexible storage block without performing an erase operation on theflash block the update data is located.

FIG. 3 shows illustrative embodiments of a flexible storage volumehaving multiple flexible storage blocks. In FIG. 3, the flexible storagevolume 301, which may be similar to the flexible storage volume 160 ofFIG. 1, may contain, among other fields and components, one or moreflexible storage blocks 310, 320, and 330. Each of the flexible storageblocks 310, 320, and 330 may contain, among other fields and components,an index field (e.g., index field 311), a next pointer field (e.g., NEXTfield 312), a configuration field (e.g., CFG field 313), and one or moredata clusters (not shown in FIG. 3). A flash storage module (similar tothe flash storage module 122 of FIG. 1, not shown in FIG. 3) mayconstruct a block link among the flexible storage blocks 310 and 320, byusing the next pointer fields. For example, the next pointer field 312in the flexible storage block 310 may store a block address of theflexible storage block 320. Linking of the flexible storage blocks intoa block link may allow data clusters to be distributed across theseflexible storage blocks. Further, each configuration field in a specificflexible storage block may configure a size of the data clusters in thespecific flexible storage block.

In some embodiments, each flexible storage block may contain anavailability map 340 having a set of entries each of which may beassociated with a specific data cluster in the flexible storage block.The entries in the availability map 340 may be initialized with a valuethat contains multiple “1” bits with no “0” bits. After the flashstorage module allocates a data cluster, it may add an entry to theavailability map 340 by performing a partial-update operation. Thepartial-update operation may change one or more “1” bits in theavailability map 340 to “0” bits, with “1” meaning available and “0”meaning not available. Afterward, the flash storage module may traversethe availability map 340 to identify whether there is any spaceavailable in the flexible storage block. For example, the flash storagemodule may determine that there are three data clusters in the flexiblestorage block, since there are three entries in the availability map 340having “0” bits. Based on the size of these data clusters, the flashstorage module can determine how much storage space left in the flexiblestorage block.

In some embodiments, each flexible storage block may contain a validitymap 350 having a set of entries each of which may be associated with aspecific data cluster in the flexible storage block. The entries in thevalidity map 350 may be initialized with a value that contains multiple“1” bits with no “0” bits. After the flash storage module invalidate adata cluster, it may change an entry associated with the data cluster inthe validity map 350 by performing a partial-update operation. Thepartial-update operation may change one or more “1” bits in the validitymap 350 to “0” bits, with “1” meaning valid and “0” meaning invalid.Afterward, the flash storage module may traverse the validity map 350 toidentify the invalidated data clusters in the flexible storage block.

In an illustrative example, a flexible storage block 310 may have a sizeof about 64 KB (kilo-bytes), and the CFG field 313 may define that eachof the data clusters in the flexible storage block 310 having a size of32 bytes. Further, the FAT table may utilize about 4 KB of space, withthe availability map and the validity map taking about 256 bytes ofspace, in the flexible storage block 310. Thus, the remaining usablespace of the flexible storage block 310 may be around 59 KB; and theflash storage module may construct about 1800 data clusters based on theremaining usable space in the flexible storage block 310.

In some embodiments, after a flexible storage block has gone throughmultiple rounds of updates, there might be a large number of dataclusters in the flexible storage block that are invalid and taking upstorage spaces. In this case, the flash storage module may conduct areconstruct process to rebuild the flexible storage block. Specifically,the flash storage module may utilize the availability map 340 and thevalidity map 350 in the flexible storage block to determine a percentageof the data clusters in the flexible storage block that are invalid. Forexample, the flash storage module may identify a total number of dataclusters in the flexible storage block by counting the entries in theavailability map 340 that are associated with the allocated dataclusters. The flash storage module may then identify a number of invaliddata clusters by counting the entries in the validity map that aremarked as invalid. Upon a determination that the percentage of invaliddata clusters is above a particular and configurable threshold (e.g.,50%), the flash storage module may initiate the reconstruction process.

In some embodiments, the flash storage module may allocate a newflexible storage block 330 in the flexible storage volume 301 toreconstruct the flexible storage block 310. The flash storage module mayidentify the valid data clusters (e.g., data clusters 314, 318, 319, and317, assuming the modified data could be stored in two data clusters, ordata clusters 314, 318, 319, and 324) in the flexible storage block 310based on its validity map, and allocate an equal number of data clusters(e.g., data clusters 334, 335, 336, and 337) in the new flexible storageblock 330. Afterward, the flash storage module may copy the data storedin the valid data clusters of the flexible storage block 310 to thenewly allocated data clusters in the new flexible storage block. Forexample, the flash storage module may copy data cluster 314 to datacluster 334, data cluster 318 to data cluster 335, data cluster 319 todata cluster 336, and data cluster 317 to data cluster 337. Afterward,the flash storage module may set up the cluster links among the dataclusters. For example, if in the flexible storage block 310, the datacluster 315 becomes invalid for having its second pointer referencingthe data cluster 318, the flash storage module may construct the clusterlink in the flexible storage block 330 by having the data cluster 334directly referencing the data cluster 335.

FIG. 4 shows a flow diagram of an illustrative embodiment of a processto update data stored in a flexible storage block. The process 401 mayinclude one or more operations, functions, or actions as illustrated byblocks 410, 420, 430, 440, and 450, which may be performed by hardware,software and/or firmware. The various blocks are not intended to belimiting to the described embodiments. For example, for this and otherprocesses and methods disclosed herein, the operations performed in theprocesses and methods may be implemented in differing order.

Furthermore, the outlined operations are only provided as examples, andsome of the operations may be optional, combined into fewer operations,or expanded into additional operations without detracting from theessence of the disclosed embodiments. Although the blocks areillustrated in a sequential order, these blocks may also be performed inparallel, and/or in a different order than those described herein. Insome embodiments, machine-executable instructions for the process 401may be stored in memory or other tangible non-transitorycomputer-readable storage medium, executed by a processor, and/orimplemented in a flexible storage management system.

At block 410 (“Maintain a cluster link in a flexible storage block tostore a file, wherein the cluster link links together a plurality ofdata clusters”), a flash storage module of a flexible storage managementsystem may be configured to maintain a cluster link in a flexiblestorage block to store a file. The cluster link may contain a pluralityof data clusters which utilize storage spaces (or are storage spaces)provided by one or more solid state devices. Further, the flash storagemodule may allocate the plurality of data clusters in the flexiblestorage block, and each of the plurality of data clusters may contain acorresponding first pointer and a corresponding second pointer. Theflash storage module may form the cluster link by linking the pluralityof data clusters. Specifically, for two data clusters that may beadjacent to each other in the cluster link, one data cluster's firstpointer may refer to the other data cluster.

In some embodiments, the flash storage module may mark each of theplurality of data clusters' second pointer with a default/initial valueindicating validity. The default/initial value may contain one or more 1bits with no 0 bits. The flash storage module may also add a FAT entryto a file allocation table (FAT) in the flexible storage block toassociate the file with the cluster link. The flash storage module maythen store the file in the plurality of data clusters of the clusterlink. Upon receiving a read request to access the file, the flashstorage module may traverse the plurality of data clusters by firstlocating the cluster link based on the FAT entry. During traversing thecluster link, for a specific data cluster in the cluster link, upon adetermination that the specific data cluster's second pointer indicatesthe specific data cluster is valid, the flash storage module maycontinue traversing the plurality of data clusters utilizing thespecific data cluster's first pointer. Upon a determination that thespecific data cluster's second pointer indicates the specific datacluster is not valid, the flash storage module may continue traversingthe plurality of data clusters utilizing the specific data cluster'ssecond pointer.

At block 420 (“In response to a request to update data stored in a firstdata cluster, allocate a second data cluster to the cluster link tostore the updated data”), the flash storage module may receive an updaterequest to update data stored in a first data cluster amongst theplurality of data clusters. Rather than applying the update directly onthe first data cluster, the flash storage module may allocate a seconddata cluster to store the updated data. In other words, the second datacluster may be a newly created data cluster and is not one of theplurality of data clusters originally in the cluster link.

At block 430 (“Link the second data cluster to the cluster link”), theflash storage module may link the second data cluster to the clusterlink. The flash storage module may assign the first data cluster's firstpointer to the second data cluster's first pointer, and update the firstdata cluster's second pointer to refer to the second data cluster. Thus,the second data cluster may take the first data cluster's place in thecluster link, and the updated second pointer in the first data clustermay indicate that the first data cluster being invalid. In other words,the linking of the second data cluster to the cluster link invalidatesthe first data cluster in the cluster link.

In some embodiments, the update request may request to append data tothe file. In this case, the flash storage module may allocate a thirddata cluster to the cluster link to store the appended data.Specifically, the flash storage module may update the first pointer ofthe tail data cluster in the cluster link to point to the third datacluster. Thus, the third data cluster may be located at the end of thecluster link, and may be deemed the new tail data cluster of the clusterlink. In some embodiments, the update request may request to delete datastored in a fourth data cluster of the cluster link. In this case, theflash storage module may identify a next data cluster that is subsequentto the fourth data cluster in the cluster link, and then update thefourth data cluster's second pointer to refer to the next data cluster.

At block 440 (“Direct a read request for the first data cluster to thesecond data cluster”), upon a determination that the first datacluster's second pointer does not contain the default/initial value, theflash storage module may direct a request for the first data cluster tothe second data cluster using the first data cluster's second pointer.Specifically, the flash storage module may also evaluate the second datacluster's second pointer for validity.

At block 450 (“Upon a determination that a percentage of invalid dataclusters is higher than a threshold, reconstruct the cluster link”),upon a determination that a percentage of invalid data clusters in theplurality of data clusters is higher than a particular and configurablethreshold, the flash storage module may reconstruct the cluster linkbased on those of the plurality of data clusters that are valid. Forexample, the flash storage module may allocate a set of data clusters inanother flexible storage block, and copy the valid data clusters in theflexible storage block to the set of data clusters. Afterward, the flashstorage module may form the cluster link by linking the set of dataclusters using each of the set of data clusters' corresponding firstpointer.

FIG. 5 shows a flow diagram of an illustrative embodiment of a processto maintain a flexible storage volume having multiple flexible storageblocks. The process 501 may include one or more operations, functions,or actions as illustrated by blocks 510, 520, 530, 540, and 550, whichmay be performed by hardware, software and/or firmware. The variousblocks are not intended to be limiting to the described embodiments. Forexample, for this and other processes and methods disclosed herein, theoperations performed in the processes and methods may be implemented indiffering order.

Furthermore, the outlined operations are only provided as examples, andsome of the operations may be optional, combined into fewer operations,or expanded into additional operations without detracting from theessence of the disclosed embodiments. Although the blocks areillustrated in a sequential order, these blocks may also be performed inparallel, and/or in a different order than those described herein. Insome embodiments, machine-executable instructions for the process 501may be stored in memory or other tangible non-transitorycomputer-readable storage medium, executed by a processor, and/orimplemented in a flexible storage management system.

At block 510 (“Maintain a plurality of flexible storage blocks”), aflexible storage management system may be configured to maintain aflexible storage volume having a plurality of flexible storage blocksthat are utilizing storage spaces provided by one or more solid statedevices. With respect to a specific flexible storage block in theflexible storage volume, the specific flexible storage block may containa configuration field to configure a cluster size associated with aplurality of data clusters in the specific flexible storage block. Thespecific flexible storage block may contain an index field to refer toanother flexible storage block in the flexible storage volume.

In some embodiments, the specific flexible storage block may contain anavailability map for the purpose of identifying available space,allocating new data clusters, and storing data. The specific flexiblestorage block may also contain a validity map for identifying those dataclusters in the each of the plurality of specific flexible storage blockthat contain valid data. The specific flexible storage block may furthercontain a file allocation table (FAT) having a FAT entry whichassociates a file with a cluster link in the specific flexible storageblock. Alternatively, the flexible storage volume may maintain the FATfor associating the file with the cluster link.

At block 520 (“Construct a cluster link having a plurality of dataclusters in the plurality of flexible storage blocks”), the flashstorage module may construct a cluster link to store a file. The clusterlink may contain a plurality of data clusters each of which is locatedin one of the plurality of flexible storage blocks. In some embodiments,in response to a read request to access the file, the flash storagemodule may traverse the plurality of data clusters to retrieve dataassociated with the file. Specifically, upon a determination that thespecific data cluster in the cluster link is valid, the flash storagemodule may continue the traversing of the plurality of data clustersfollowing a first link direction indicated by the specific data cluster.The first link direction may be a first pointer in the specific datacluster. Further, upon a determination that the specific data cluster isnot valid, the flash storage module may continue the traversing of theplurality of data clusters following a second link direction indicatedby the specific data cluster. The second link may be a second pointer inthe specific data cluster.

At block 530 (“In response to an update request, identify a first datacluster in the plurality of data clusters”), in response to an updaterequest to update the file, the flash storage module may identify afirst data cluster in the plurality of data clusters that is associatedwith the updated data in the file. At block 540 (“Allocate a second datacluster to store updated data”), the flash storage module may allocate asecond data cluster in any one of the plurality of flexible storageblocks that has available space to store the updated data; and assignthe first data cluster's first link direction to the second datacluster's first link direction.

At block 550 (“Link the second data cluster to the cluster link, therebyinvalidating the first data cluster in the cluster link”), the flashstorage module may link the second data cluster to the cluster link byassigning the first data cluster's second link direction to refer to thesecond data cluster. Specifically, the assigning of the first datacluster's second link direction may involve updating one or more “1”bits in the second link direction to “0” bits, and the linking of thesecond data cluster to the cluster link invalidates the first datacluster in the cluster link.

FIG. 6 is a block diagram of an illustrative embodiment of a computerprogram product 600 to implement a method to update data stored in astorage block. Computer program product 600 may include a signal bearingmedium 602. Signal bearing medium 602 may include one or more sets ofexecutable instructions 604 that, when executed by, for example, aprocessor, may provide the features and operations described above.Thus, for example, referring to FIG. 1, the flexible storage managementsystem and/or the flash storage module may undertake one or more of theoperations shown in at least FIG. 4 in response to the instructions 604.

In some implementations, signal bearing medium 602 may encompass anon-transitory computer readable medium 606, such as, but not limitedto, a hard disk drive, a Compact Disc (CD), a Digital Versatile Disk(DVD), a digital tape, memory, etc. In some implementations, signalbearing medium 602 may encompass a recordable medium 608, such as, butnot limited to, memory, read/write (R/W) CDs, R/W DVDs, etc. In someimplementations, signal bearing medium 602 may encompass acommunications medium 610, such as, but not limited to, a digital and/oran analog communication medium (e.g., a fiber optic cable, a waveguide,a wired communications link, a wireless communication link, etc.). Thus,for example, referring to FIG. 1, computer program product 600 may bewirelessly conveyed to the flexible storage management system 110 bysignal bearing medium 602, where signal bearing medium 602 is conveyedby communications medium 610 (e.g., a wireless communications mediumconforming with the IEEE 802.11 standard). Computer program product 600may be recorded on non-transitory computer readable medium 606 oranother similar recordable medium 608.

FIG. 7 shows a block diagram of an illustrative embodiment of an examplecomputer system 700. In a very basic configuration 701, the computersystem 700 may include one or more processors 710 and a system memory720. A memory bus 730 may be used for communicating between theprocessor 710 and the system memory 720.

Depending on the desired configuration, processor 710 may be of any typeincluding but not limited to a microprocessor (μP), a microcontroller(μC), a digital signal processor (DSP), or any combination thereof.Processor 710 can include one or more levels of caching, such as a levelone cache 711 and a level two cache 712, a processor core 713, andregisters 714. The processor core 713 can include an arithmetic logicunit (ALU), a floating point unit (FPU), a digital signal processingcore (DSP Core), or any combination thereof. A memory controller 715 canalso be used with the processor 710, or in some implementations thememory controller 715 can be an internal part of the processor 710.

Depending on the desired configuration, the system memory 720 may be ofany type including but not limited to volatile memory (such as RAM),non-volatile memory (such as ROM, flash memory, etc.) or any combinationthereof. The system memory 720 may include an operating system 721, oneor more applications 722, and program data 724. The application 722 mayinclude a flash storage management application 723 that is arranged toperform the operations as described herein including at least theoperations described with respect to the process 401 of FIG. 4 and/ordescribed elsewhere in this disclosure. The program data 724 may includecluster link 725 to be accessed by the flash storage managementapplication 723. In some embodiments, the flash storage module 122 ofFIG. 1 may be implemented as the application 722 to operate with theprogram data 724 on the operating system 721. Specifically, the flashstorage module 122 may construct the cluster link 725 to store data fora file. This described basic configuration is illustrated in FIG. 7 bythose components within dashed line 701.

Computing device 700 may have additional features or functionality, andadditional interfaces to facilitate communications between basicconfiguration 701 and any required devices and interfaces. For example,a bus/interface controller 740 may be used to facilitate communicationsbetween basic configuration 701 and one or more data storage devices 750via a storage interface bus 741. Data storage devices 750 may beremovable storage devices 751, non-removable storage devices 752, or acombination thereof. Examples of removable storage and non-removablestorage devices include magnetic disk devices such as flexible diskdrives and hard-disk drives (HDD), optical disk drives such as compactdisk (CD) drives or digital versatile disk (DVD) drives, solid statedrives (SSDs), and tape drives to name a few. Example computer storagemedia may include volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage ofinformation, such as computer readable instructions, data structures,program modules, or other data.

System memory 720, removable storage devices 751, and non-removablestorage devices 752 are examples of computer storage media. Computerstorage media includes, but is not limited to, RAM, ROM, EEPROM, flashmemory or other memory technology, CD-ROM, digital versatile disks(DVDs) or other optical storage, magnetic cassettes, magnetic tape,magnetic disk storage or other magnetic storage devices, or any othermedium which may be used to store the desired information and which maybe accessed by computing device 700. Any such computer storage media maybe part of computing device 700.

Computing device 700 may also include an interface bus 742 forfacilitating communication from various interface devices (e.g., outputdevices 760, peripheral interfaces 770, and communication devices 780)to basic configuration 701 via bus/interface controller 740. Exampleoutput devices 760 include a graphics processing unit 761 and an audioprocessing unit 762, which may be configured to communicate to variousexternal devices such as a display or speakers via one or more A/V ports763. Example peripheral interfaces 770 include a serial interfacecontroller 771 or a parallel interface controller 772, which may beconfigured to communicate with external devices such as input devices(e.g., keyboard, mouse, pen, voice input device, touch input device,etc.) or other peripheral devices (e.g., printer, scanner, etc.) via oneor more I/O ports 773. An example communication device 780 includes anetwork controller 781, which may be arranged to facilitatecommunications with one or more other computing devices 790 over anetwork communication link via one or more communication ports 782. Insome implementations, computing device 700 includes a multi-coreprocessor, which may communicate with the host processor 710 through theinterface bus 742.

The network communication link may be one example of a communicationmedia. Communication media may typically be embodied by computerreadable instructions, data structures, program modules, or other datain a modulated data signal, such as a carrier wave or other transportmechanism, and may include any information delivery media. A “modulateddata signal” may be a signal that has one or more of its characteristicsset or changed in such a manner as to encode information in the signal.By way of example, and not limitation, communication media may includewired media such as a wired network or direct-wired connection, andwireless media such as acoustic, radio frequency (RF), microwave,infrared (IR) and other wireless media. The term computer readable mediaas used herein may include both storage media and communication media.

Computing device 700 may be implemented as a portion of a small-formfactor portable (or mobile) electronic device such as a cell phone, apersonal data assistant (PDA), a personal media player device, awireless web-watch device, a personal headset device, an applicationspecific device, or a hybrid device that include any of the abovefunctions. Computing device 700 may also be implemented as a personalcomputer including both laptop computer and non-laptop computerconfigurations.

There is little distinction left between hardware and softwareimplementations of aspects of systems; the use of hardware or softwareis generally (but not always, in that in certain contexts the choicebetween hardware and software can become significant) a design choicerepresenting cost vs. efficiency tradeoffs. There are various vehiclesby which processes and/or systems and/or other technologies describedherein can be effected (e.g., hardware, software, and/or firmware), andthat the preferred vehicle will vary with the context in which theprocesses and/or systems and/or other technologies are deployed. Forexample, if an implementer determines that speed and accuracy areparamount, the implementer may opt for a mainly hardware and/or firmwarevehicle; if flexibility is paramount, the implementer may opt for amainly software implementation; or, yet again alternatively, theimplementer may opt for some combination of hardware, software, and/orfirmware.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples can be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. In some embodiments,several portions of the subject matter described herein may beimplemented via Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs), digital signal processors (DSPs), orother integrated formats. However, those skilled in the art willrecognize that some aspects of the embodiments disclosed herein, inwhole or in part, can be equivalently implemented in integratedcircuits, as one or more computer programs running on one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs running on one or more processors(e.g., as one or more programs running on one or more microprocessors),as firmware, or as virtually any combination thereof, and that designingthe circuitry and/or writing the code for the software and or firmwarewould be well within the skill of one of skill in the art in light ofthis disclosure. In addition, those skilled in the art will appreciatethat the mechanisms of the subject matter described herein are capableof being distributed as a program product in a variety of forms, andthat an illustrative embodiment of the subject matter described hereinapplies regardless of the particular type of signal bearing medium usedto actually carry out the distribution. Examples of a signal bearingmedium include, but are not limited to, the following: a recordable typemedium such as a floppy disk, a hard disk drive, a Compact Disc (CD), aDigital Versatile Disk (DVD), a digital tape, a computer memory, etc.;and a transmission type medium such as a digital and/or an analogcommunication medium (e.g., a fiber optic cable, a waveguide, a wiredcommunications link, a wireless communication link, etc.).

Those skilled in the art will recognize that it is common within the artto describe devices and/or processes in the fashion set forth herein,and thereafter use engineering practices to integrate such describeddevices and/or processes into data processing systems. That is, at leasta portion of the devices and/or processes described herein can beintegrated into a data processing system via a reasonable amount ofexperimentation. Those having skill in the art will recognize that atypical data processing system generally includes one or more of asystem unit housing, a video display device, a memory such as volatileand non-volatile memory, processors such as microprocessors and digitalsignal processors, computational entities such as operating systems,drivers, graphical user interfaces, and applications programs, one ormore interaction devices, such as a touch pad or screen, and/or controlsystems including feedback loops and control motors (e.g., feedback forsensing position and/or velocity; control motors for moving and/oradjusting components and/or quantities). A typical data processingsystem may be implemented utilizing any suitable commercially availablecomponents, such as those typically found in datacomputing/communication and/or network computing/communication systems.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to”,etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

I claim:
 1. A method to update data stored in a storage block,comprising: maintaining, by a flash storage module, a cluster link inthe storage block to store a file, wherein the cluster link linkstogether a plurality of data clusters that are storage spaces providedby one or more solid state devices; in response to a first request toupdate data stored in a first data cluster amongst the plurality of dataclusters, allocating, by the flash storage module, a second data clusterto store the updated data; and linking, by the flash storage module, thesecond data cluster to the cluster link, wherein the linking the seconddata cluster to the cluster link invalidates the first data cluster inthe cluster link.
 2. The method as recited in claim 1, wherein themaintaining the cluster link comprises: allocating the plurality of dataclusters in the storage block, wherein each of the plurality of dataclusters include a corresponding first pointer and a correspondingsecond pointer; forming the cluster link by linking the plurality ofdata clusters, wherein for a third data cluster and a fourth datacluster adjacent to each other in the cluster link, the third datacluster's first pointer refers to the fourth data cluster; and markingeach of the plurality of data clusters' second pointer with a defaultvalue indicating validity, wherein the default value contains one ormore 1 bits with no 0 bits.
 3. The method as recited in claim 2, whereinthe maintaining the cluster link further comprises: adding an entry to afile allocation table (FAT) in the storage block, wherein the entryassociates the file with the cluster link; storing the file in theplurality of data clusters; and in response to receiving a request toaccess the file, traversing the plurality of data clusters by locatingthe cluster link based on the entry.
 4. The method as recited in claim2, wherein the linking the second data cluster to the cluster linkcomprises: assigning the first data cluster's first pointer to thesecond data cluster's first pointer; and updating the first datacluster's second pointer to refer to the second data cluster, whereinthe updated second pointer indicates invalidity of the first datacluster.
 5. The method as recited in claim 4, further comprising: inresponse to a determination that the first data cluster's second pointerdoes not contain the default value, directing a request for the firstdata cluster to the second data cluster using the first data cluster'ssecond pointer.
 6. The method as recited in claim 3, wherein thetraversing the plurality of data clusters comprises: for a specific datacluster in the cluster link, in response a first determination that thespecific data cluster's second pointer indicates the specific datacluster is valid, traversing the plurality of data clusters utilizingthe specific data cluster's first pointer; and in response to a seconddetermination that the specific data cluster's second pointer indicatesthe specific data cluster is not valid, traversing the plurality of dataclusters utilizing the specific data cluster's second pointer.
 7. Themethod as recited in claim 1, further comprising: in response to asecond request to append data to the file, allocating a third datacluster to the cluster link to store the appended data, wherein thethird data cluster is located at an end of the cluster link.
 8. Themethod as recited in claim 2, further comprising: in response to asecond request to delete data stored in the third data cluster, updatingthe third data cluster's second pointer to refer to the fourth datacluster.
 9. The method as recited in claim 3, further comprising: inresponse to a determination that a percentage of invalid data clustersin the plurality of data clusters is higher than a threshold,reconstructing the cluster link based on those of the plurality of dataclusters that are valid.
 10. The method as recited in claim 9, whereinthe reconstructing the cluster link comprises: allocating a set of dataclusters in another storage block, wherein each of the set of dataclusters contains data copied from a corresponding data cluster amongstthose of the plurality of data clusters that are valid; and forming thecluster link by linking the set of data clusters using each of the setof data clusters' corresponding first pointer.
 11. A method to storedata in a storage volume, comprising: maintaining, by a flash storagemodule, a plurality of storage blocks utilizing storage spaces providedby one or more solid state devices; constructing, by the flash storagemodule, a cluster link to store a file, wherein the cluster link linkstogether a plurality of data clusters each of which is a storagelocation that is located in one of the plurality of storage blocks; inresponse to an update request to update the file, identifying, by theflash storage module, a first data cluster in the plurality of dataclusters that is associated with updated data in the file; allocating,by the flash storage module, a second data cluster in any one of theplurality of storage blocks that has available space to store theupdated data; and linking, by the flash storage module, the second datacluster to the cluster link, wherein the linking the second data clusterto the cluster link invalidates the first data cluster in the clusterlink.
 12. The method as recited in claim 11, wherein maintaining theplurality of storage blocks includes maintaining, for each of theplurality of storage blocks: a configuration field to configure acluster size associated with each of the plurality of data clusters; anavailability map to identify available space in the each of theplurality of storage blocks that are available to store data; and anvalidity map to identify those data clusters in the each of theplurality of storage blocks that contain valid data.
 13. The method asrecited in claim 11, wherein for a first storage block and a secondstorage block that are linked to each other, maintaining the pluralityof storage blocks includes maintaining an index field of the firststorage block to refer to the second storage block.
 14. The method asrecited in claim 11, wherein the storage volume is configured with afile allocation table (FAT) having a FAT entry which associates the filewith the cluster link, and the method further comprising: in response toa read request to access the file, traversing the plurality of dataclusters to retrieve data associated with the file, wherein for aspecific data cluster in the plurality of data clusters, in response toa first determination that the specific data cluster is valid,continuing the traversing of the plurality of data clusters following afirst link direction indicated by the specific data cluster; and inresponse to a second determination that the specific data cluster is notvalid, continuing the traversing of the plurality of data clustersfollowing a second link direction indicated by the specific datacluster.
 15. The method as recited in claim 11, wherein the allocatingthe second data cluster comprises: assigning the first data cluster'sfirst link direction to the second data cluster's first link direction.16. The method as recited in claim 11, wherein the linking the seconddata cluster comprises: assigning the first data cluster's second linkdirection to refer to the second data cluster, wherein assigning thefirst data cluster's second link direction involves updating one or more“1” bits in the second link direction to “0” bits.
 17. A system tomanage flash data storage, comprising: a solid state device configuredto provide a plurality of flash pages; and a flash storage modulecoupled with the solid state device, wherein the flash storage module isconfigured to: maintain a storage block utilizing storage spacesprovided by the solid state device, construct a cluster link to store afile in the storage block, wherein the cluster link links together aplurality of data clusters each of which utilizes one of the pluralityof flash pages to store data associated with the file, in response to arequest to update data stored in a first data cluster amongst theplurality of data clusters, allocate a second data cluster in thestorage block to store the updated data, and link the second datacluster to the cluster link to invalidate the first data cluster. 18.The system as recited in claim 17, wherein the flash storage module isfurther configured to allocate the second data cluster without an updateof the data stored in the first data cluster and associated with thefile.
 19. The system as recited in claim 17, wherein the flash storagemodule is further configured to link the second data cluster to thecluster link by a marking of the first data cluster as invalid, and themarking of the first data cluster does not involve a change of any “0”bits in the plurality of flash pages to “1” bits.
 20. The system asrecited in claim 19, wherein the flash storage module is furtherconfigured to link the second data cluster to the cluster link bycopying the first data cluster's association with a next data cluster inthe cluster link to the second data cluster.
 21. A non-transitorycomputer-readable storage medium, having a set of instructions which,when executed by a computing processor, cause the computing processor toperform a method to update data stored in a storage block, the methodcomprising: maintaining, by a flash storage module, a cluster link inthe storage block to store a file, wherein the cluster link linkstogether a plurality of data clusters that are storage spaces providedby one or more solid state devices; in response to a first request toupdate data stored in a first data cluster amongst the plurality of dataclusters, allocating, by the flash storage module, a second data clusterto the cluster link to store the updated data; and linking, by the flashstorage module, the second data cluster to the cluster link, wherein thelinking the second data cluster to the cluster link invalidates thefirst data cluster in the cluster link.
 22. A non-transitorycomputer-readable storage medium, having a set of instructions which,when executed by a computing processor, cause the computing processor toperform a method to store data in a storage volume, the methodcomprising: maintaining, by a flash storage module, a plurality ofstorage blocks utilizing storage spaces provided by one or more solidstate devices; constructing, by the flash storage module, a cluster linkto store a file, wherein the cluster link links together a plurality ofdata clusters each of which is a storage location that is located in oneof the plurality of storage blocks; in response to an update request toupdate the file, identifying, by the flash storage module, a first datacluster in the plurality of data clusters that is associated withupdated data in the file; allocating, by the flash storage module, asecond data cluster in any one of the plurality of storage blocks thathas available space to store the updated data; and linking, by the flashstorage module, the second data cluster to the cluster link, wherein thelinking the second data cluster to the cluster link invalidates thefirst data cluster in the cluster link.